If in fact it's wet fowl pox, you can remove the lesions and swab the mouth with iodine. There will be alot of blood but the iodine should prevent reinfection. You have to remove ALL lesions and if there are some in the trachea or down in the esophagus, there's nothing you can do. Lesions can also infect the crop, this also true for canker.
The bad thing about canker is that birds are carriers for life once infected, not so with fowl pox. However, lesions are highly infective to other birds, particularly birds with dry pox. Birds can have both dry and wet pox at the same time. After it slowly passes through a flock, birds are immune to that particular strain for life.
Birds with wet pox have about a 50% chance of surviving.